This invention is directed to form, fill and seal pouch packaging machine pull wheels that have two circumferentially extending, but axially separated flanges located on a hub and an elastomeric body located between, over and outside of the flanges.
A variety of products are packaged in film pouches that are formed, filled and sealed on appropriate packaging machines. These machines utilize continuous rolls of film. A pouch is formed from the film, filled with a product and then sealed in a continuous operation. These machines are referred to as form, fill and seal pouch packaging machines.
To form pouches on such form, fill and seal pouch packaging machines, side seams are first formed between front and back films via side seals. A cross seal is then utilized to form a bottom seam. This three sided pouch is then filled with product and the machine in indexed. A further cross seal is now utilized to form the top seam on the filled pouch and concurrently the bottom seam on the next partly formed, but still empty pouch. The empty pouch is filed and the machine is once again indexed to continue the cycle.
When the machine is indexed, pull rollers are utilized to engage the film and advance it with respect to both the side seals and the cross seals. A typical pouch packaging machine is capable of concurrently forming a linear array of side to side pouches across the width of the machine. The number of side by side pouches that are concurrently formed can vary from a single pouch, when large pouches are being formed, to multiple pouches, when narrow pouches are being formed. Depending upon the number of pouches that are being formed across the width of the machine, a number of side seams will be formed between the films. An equal number of pull wheels are generally utilized in conjunction with the side seams to advance the film on the machine.
The pull wheels are generally utilized in opposing pairs. A front member of the pair is located on one side of the film and a back member of the pair is located on the other side of the film. Normally, all of the front members of pairs of pull wheels are located on a single shaft on the front side of the film and in a like manner all of the back members of the pairs are located on a single shaft on the back side of the film.
Normally all the front pull wheels, or all the back pull wheels or both sets of pull wheels will be fixed to their appropriate shafts so as to be positively rotated in conjunction with rotation of the shafts. Each time the machine is indexed the drive shaft is rotated and this in turn rotates the pull wheels. After each indexing of the machine, the pull wheel drive shaft is stopped and this in turn stops the pull wheels. The pull wheels are thus started and stopped with each index of the machine. This acceleration and deceleration of the pull wheels with each indexing of the machine is very stressful to the normal elastomeric covering that is located on the pull wheels for gripping the film. Since the typical form, fill and seal pouch packaging machine are operated at a high rate of speed, the pull wheels are continuously being accelerated and decelerated.
While presently known pull wheels are useful over many cycles, because the pouch packaging machines are run at high rates of speed, pull wheel failure can occur in a matter of days. If the elastomeric material that is normally laminated to the pull wheel delaminates or otherwise disintegrates, splits or the like, the machine must be taken off line and the pull wheel or pull wheels replaced. This is a time consuming and thus labor intensive operation. Because replacement of the pull wheels requires taking the form, fill and seal pouch packaging machine off line, it is both an annoyance and an economic disadvantage.
Heretofore, attempts have been made to increase the life time of form, fill and seal pouch packaging machine pull wheels by improving the elastomers that are utilized on the pull wheels. However, since to advance the film on the packaging machine the elastomer of the pull wheel must grip the film without damaging it, certain properties of the elastomer, i.e. suppleness and flexibility, must be maintained. Thus, replacement of the elastomeric material alone has not solved the need for pull wheels having longer, useful lifetimes.